SUMMARY
The paper presents results of wear tests of hot-work steels 4H5W2FS, AMS 6437E and cold- work steels ASTM A681, Ch12FS, with surface hardened by Carbo carburizing process. The carburizing process was carried out in powder pack during for 6 h. Wear tests were made by the three cylinders -cone method. Wear velocity was 0.58 m/s, unit load was 50 MPa and 400MPa, wear path was 3470 m. SAE30 oil was applied at the rate of 30 drops per minute. Investigated factors were: morphology, depth and microhardness of obtained cases, their microstructure, as well as phase composition.

Keywords
Cold- work steels, hod- work steels, carburizing, structure, wear by friction..

¹Instytut Mechaniki Precyzyjnej, Warszawa